77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
package snapshot
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"io"
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"github.com/klauspost/compress/zstd"
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)
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// Manifest represents the structure of a snapshot's blob manifest
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type Manifest struct {
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SnapshotID string `json:"snapshot_id"`
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Timestamp string `json:"timestamp"`
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BlobCount int `json:"blob_count"`
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TotalCompressedSize int64 `json:"total_compressed_size"`
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Blobs []BlobInfo `json:"blobs"`
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}
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// BlobInfo represents information about a single blob in the manifest
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type BlobInfo struct {
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Hash string `json:"hash"`
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CompressedSize int64 `json:"compressed_size"`
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}
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// DecodeManifest decodes a manifest from a reader containing compressed JSON
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func DecodeManifest(r io.Reader) (*Manifest, error) {
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// Decompress using zstd
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zr, err := zstd.NewReader(r)
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if err != nil {
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return nil, fmt.Errorf("creating zstd reader: %w", err)
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}
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defer zr.Close()
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// Decode JSON manifest
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var manifest Manifest
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err = json.NewDecoder(zr).Decode(&manifest)
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if err != nil {
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return nil, fmt.Errorf("decoding manifest: %w", err)
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}
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return &manifest, nil
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}
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// EncodeManifest encodes a manifest to compressed JSON
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func EncodeManifest(manifest *Manifest, compressionLevel int) ([]byte, error) {
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// Marshal to JSON
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jsonData, err := json.MarshalIndent(manifest, "", " ")
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if err != nil {
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return nil, fmt.Errorf("marshaling manifest: %w", err)
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}
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// Compress using zstd
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var compressedBuf bytes.Buffer
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writer, err := zstd.NewWriter(&compressedBuf, zstd.WithEncoderLevel(zstd.EncoderLevelFromZstd(compressionLevel)))
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if err != nil {
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return nil, fmt.Errorf("creating zstd writer: %w", err)
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}
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_, err = writer.Write(jsonData)
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if err != nil {
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_ = writer.Close()
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return nil, fmt.Errorf("writing compressed data: %w", err)
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}
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err = writer.Close()
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if err != nil {
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return nil, fmt.Errorf("closing zstd writer: %w", err)
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}
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return compressedBuf.Bytes(), nil
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}
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